diff --git a/src/nvimage/ImageIO.cpp b/src/nvimage/ImageIO.cpp
index 87a33f9..69954a7 100644
--- a/src/nvimage/ImageIO.cpp
+++ b/src/nvimage/ImageIO.cpp
@@ -116,7 +116,7 @@ Image * nv::ImageIO::load(const char * fileName, Stream & s)
 	return NULL;
 }
 
-bool nv::ImageIO::save(const char * fileName, Stream & s, Image * img)
+bool nv::ImageIO::save(const char * fileName, Stream & s, const Image * img)
 {
 	nvDebugCheck(fileName != NULL);
 	nvDebugCheck(s.isSaving());
@@ -131,7 +131,7 @@ bool nv::ImageIO::save(const char * fileName, Stream & s, Image * img)
 	return false;
 }
 
-bool nv::ImageIO::save(const char * fileName, Image * img)
+bool nv::ImageIO::save(const char * fileName, const Image * img)
 {
 	nvDebugCheck(fileName != NULL);
 	nvDebugCheck(img != NULL);
diff --git a/src/nvimage/ImageIO.h b/src/nvimage/ImageIO.h
index 8e64093..852217e 100644
--- a/src/nvimage/ImageIO.h
+++ b/src/nvimage/ImageIO.h
@@ -19,8 +19,8 @@ namespace nv
 		NVIMAGE_API FloatImage * loadFloat(const char * fileName);
 		NVIMAGE_API FloatImage * loadFloat(const char * fileName, Stream & s);
 		
-		NVIMAGE_API bool save(const char * fileName, Stream & s, Image * img);
-		NVIMAGE_API bool save(const char * fileName, Image * img);
+		NVIMAGE_API bool save(const char * fileName, Stream & s, const Image * img);
+		NVIMAGE_API bool save(const char * fileName, const Image * img);
 		NVIMAGE_API bool saveFloat(const char * fileName, const FloatImage * fimage, uint base_component, uint num_components);
 
 		NVIMAGE_API Image * loadTGA(Stream & s);